1. Technical Field
The embodiments herein generally relate to law enforcement technologies and security, and more particularly to techniques for determining the origin and direction of travel of supersonic projectiles.
2. Description of the Related Art
Systems and methods are known that can determine the general location of the sniper and trajectory of supersonic projectiles, such as bullets and artillery shells, by measuring parameters associated with the shockwave generated by a projectile. Current systems, however, generally require a distributed array of acoustic sensors to detect the arrival times, amplitudes and frequency characteristics of a projectile's shockwave and the muzzle blast from a firearm. In addition, such systems typically require real-time operating systems (e.g., UNIX, LINUX, etc.) and generally require an elaborate time synchronization mechanism so that all the deployed sensors have a common time reference to determine the exact time of arrival for both shockwave and the muzzle blast for supersonic gun fire with common reference time frame.
Conventional systems typically employ an antenna with a plurality of acoustic sensors, which can be relatively closely spaced (e.g., 1 meter apart) or widely dispersed (e.g., mounted on a vehicle or carried by soldiers on a battlefield), with each sensor measuring shockwave pressure omni-directionally at its respective location. One exemplary antenna may include, for example, a total of seven omni-directional microphones, with six microphones distributed over the surface of a sphere (approx. diameter 1 m) and the seventh microphone located in the center of the sphere. Other exemplary antennae employ four microphones arranged in a tetrahedron formation that are amenable to carry on by a person. In general, the microphones in existing systems are arranged in an array configuration and their output is collected by a common data collection unit with a common time reference. Additionally, existing array based sniper localization systems require the orientation of the array with respect to true north to be determined in order to estimate the location of the sniper and the trajectory of the bullet.
Such array based sensors systems, however, are less suitable for man-wearable systems. In addition, when the sensors are distributed, time synchronization among the sensors is critical. If an operating system that is not a real-time operating system is employed (e.g., Windows® CE operating system), the synchronization among the sensors is not guaranteed. As a result, the time of arrival estimates of different events (e.g., shockwave and the muzzle blast from a firearm) could be off by 1-2 seconds making the localization of the firearm impossible.